The present disclosure relates broadly to the field of solar power generation. More particularly, this disclosure relates to systems by which solar energy is captured in solid particles and transferred to a heat exchanger to produce power. These solar receiver designs can be used with Concentrated Solar Tower technology, also known as Concentrated Solar Power (CSP) technology, to harness the sun's energy to produce “green” electricity.
Concentrated solar power technology has been known for a substantial time. Its uses and applications stretch from heating and cooling to chemical processing to power production. Generally, solar energy is captured in a heat capture medium within a closed loop and transferred via a heat exchanger to a second medium in a second separate loop where the energy is used.
U.S. Pat. No. 3,908,632 describes the use of a gaseous carrier for transporting solid particles through a solar receiver for absorbing solar radiation, and transferring that heat energy to water or other heat exchange medium. When solid particles are used as a heat capture medium and are transported using a gaseous carrier (e.g. air), the gaseous carrier will inevitably be heated as well through convection heat exchange with the particles. The amount of heat exchange will be largely due to the high concentration, small size, large reaction surface, and high heat transfer coefficient of the particles. If the energy in the gaseous carrier is not also transferred at the heat exchanger to the second medium, the efficiency of the total solar energy capture cycle decreases due to this heat loss. The maximum temperature that the solid particles can attain in the solar receiver becomes limited by the maximum temperature acceptable to the blower that is circulating the gaseous carrier, rather than the maximum temperature acceptable to the particles themselves.
U.S. Pat. No. 4,338,919 describes the use of a mechanical apparatus for transporting solid particles through a solar receiver. However, this patent does not decouple the solids flow rate through the solar receiver with the solids flow rate through the fluidized bed heat exchanger.
In addition, solar activity is variable, meaning that a constant energy output from the heat exchanger cannot be obtained unless some sort of storage for the heat capture medium is provided.
It would be desirable to provide a solar power system that can provide increased system efficiency and flexibility.